摘要:

AbstractA model of retrograded starch molecules was proposed in our previous paper. The effect of the addition of n‐butyl alcohol or sucrose fatty acid on the retrogradation of starch was studied in this paper. The samples were prepared by repeating freeze‐thaw cycles with or without addition of complex forming agents. The samples were treated with 16% sulfuric acid as byNägeliamylodextrin preparation or a mixture of β‐amylase‐pullulanase. The residues of the acid or enzyme treatment were chromatographed. From the results of iodine titration, degree of gelatinization, X‐ray diffraction, and chain length distribution, it is discussed how the helix forming angents react with fractions of starch and prevent the retrogradation. A schematic model of the retrograded starch with helix forming agents are al

ISSN:0038-9056    

DOI:10.1002/star.19860380102

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

AbstractRetrogradation phenomenon in cooked wheat grain was investigated by means of Differential Scanning Calorimetry (DSC) and mechanical compression tests. The extent of starch retrogradation as measured by endotherm increased with time. More importantly, the onset, peak and conclusion temperatures are dependent on the storage temperature and are significantly lower for grain stored at lower temperatures. The firmness of the grain due to starch crystallization as indicated by the elastic modulus also increased with time and was higher at lower storage temperatures. Lowered storage temperature not only accelerates starch recrystallization and thus firming process of the cooked grain, but also seems to generate a different organization in the ordering of the starch.

ISSN:0038-9056    

DOI:10.1002/star.19860380103

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

AbstractThe hydrolysis of potato starch by 1‐NH2SO4/30% ethanol aqueous solution at 45°C increased linearly with increasing of hydrolysis time for 14 d. The relative crystallinity of native starch showed 0.343 and 0.350 by symmetrical reflection and transmission techniques, resp. The increasing ratio of relative crystallinity to hydrolysis time corresponded very closely with that of 1/hydrolysis residue up to 14 d. These facts suggest that only the amorphous region of the starch granules will be hydrolyzed by the acid. By differential scanning calorimetry the calorimetric enthalpy of potato starch containing about 200% moisture content was found to stay largely unchanged by acid treatment for 6 d. The swelling power at 70° and 80°C of potato starch reached to the minimum value and, moreover, from the gel‐chromatogram patterns of the acid‐treated starches, the crystalline region of the starch granules may begin to deteriorate slightly by acid treatment for more than 6 d, although the relative crystallinity by the X‐ray diffraction method increased slightly with passing of hydro

ISSN:0038-9056    

DOI:10.1002/star.19860380104

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

Abstract1) Air adsorbed on potato tuber surface can result the accidental error, decreasing the true value of tuber density. Some deviations from normal temperature do not seem to change substantialy the tuber density.2) The dry matter determination should be precisely reexamined in a special series of experiments. The improper method can introduce a systematic error, increasing or decreasing the results.3) It is necessary to compare mostly used methods of starch determination in potato tubers and to estimate the possible systematic errors.4) The various slope of the regression line: dry mater/starchvs.potato density, can be resulted by different factors as follows: the variable intercellular spaces, the proportional systematic errors in analytical determination, the variable dry matter density, and increasing (or decreasing) value of non‐starch substances.5) The intercellular spaces can result either a constant or a proportional systematic errors in the tuber density determination. They can be eliminated by vacuum infiltration procedure, which should be, however, verified.6) The dry matter determination seems to be difficult analytical problem and it has not been definitely solved until now.7) TheMaercker's constant has been until now an open question and its variability should be verified from analytical point of vie

ISSN:0038-9056    

DOI:10.1002/star.19860380105

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

AbstractWheat starch was treated for gelatinization, partial liquefaction, and subsequent further hydrolysis by extrusion cooking together with a thermostableBacillus licheniformisα‐amylase followed by batch incubation of the extrudates at 80°C. The degree of hydrolysis depended on the extrusion feed moisture content, enzyme concentration, mass temperature during extrusion cooking, and the length of the counter screw elements. The degree of hydrolysis was followed both by dextrose equivalent and by molecular weight distribution pattern as determined by high performance gel permeation chromatography. A reaction velocity model was shown to fit well to the kinetic data obtained. The enzyme was only incompletely inactivated by mercuric chloride suggesting the presence of also other than sulfhydryl dependent amyl

ISSN:0038-9056    

DOI:10.1002/star.19860380106

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

摘要:

AbstractIsosorbide is obtained by dehydration of sorbitol and therefore can be considered as a valuable product from biomass. The acid‐catalyzed reaction gives rise to different anhydro‐compounds, but also to polymer‐like products. Kinetics of sorbitol decrease, followed with the help of HPLC, shows, remarkedly, the different reactions taking place during the dehydration. Physiocochemical properties of isosorbide are also discussed: melting temperature, specific gravity, solubility. Emphasis is put on stereochemistry aspect, pointing out theendo‐exoposition of hydroxyl groupsversusthose of other isomers:exo‐exofor isoiodide andendo‐endofor isomannide. Some other properties such as: hygroscopicity ant thermal stability are also discussed. The chemical reactivity of the molecule is then described and some reactions analyzed, proving the interest of the cyclic conformation. Finally, a review of known applications i

ISSN:0038-9056    

DOI:10.1002/star.19860380107

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

ISSN:0038-9056    

DOI:10.1002/star.19860380108

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

ISSN:0038-9056    

DOI:10.1002/star.19860380109

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

ISSN:0038-9056    

DOI:10.1002/star.19860380110

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY

ISSN:0038-9056    

DOI:10.1002/star.19860380115

出版商:WILEY‐VCH Verlag GmbH    

年代:1986

数据来源: WILEY